1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
|
# vim: tabstop=4 shiftwidth=4 softtabstop=4
# Copyright (c) 2011 OpenStack Foundation.
# All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
import os
import re
class CommandFilter(object):
"""Command filter only checking that the 1st argument matches exec_path."""
def __init__(self, exec_path, run_as, *args):
self.name = ''
self.exec_path = exec_path
self.run_as = run_as
self.args = args
self.real_exec = None
def get_exec(self, exec_dirs=[]):
"""Returns existing executable, or empty string if none found."""
if self.real_exec is not None:
return self.real_exec
self.real_exec = ""
if self.exec_path.startswith('/'):
if os.access(self.exec_path, os.X_OK):
self.real_exec = self.exec_path
else:
for binary_path in exec_dirs:
expanded_path = os.path.join(binary_path, self.exec_path)
if os.access(expanded_path, os.X_OK):
self.real_exec = expanded_path
break
return self.real_exec
def match(self, userargs):
"""Only check that the first argument (command) matches exec_path."""
return os.path.basename(self.exec_path) == userargs[0]
def get_command(self, userargs, exec_dirs=[]):
"""Returns command to execute (with sudo -u if run_as != root)."""
to_exec = self.get_exec(exec_dirs=exec_dirs) or self.exec_path
if (self.run_as != 'root'):
# Used to run commands at lesser privileges
return ['sudo', '-u', self.run_as, to_exec] + userargs[1:]
return [to_exec] + userargs[1:]
def get_environment(self, userargs):
"""Returns specific environment to set, None if none."""
return None
class RegExpFilter(CommandFilter):
"""Command filter doing regexp matching for every argument."""
def match(self, userargs):
# Early skip if command or number of args don't match
if (len(self.args) != len(userargs)):
# DENY: argument numbers don't match
return False
# Compare each arg (anchoring pattern explicitly at end of string)
for (pattern, arg) in zip(self.args, userargs):
try:
if not re.match(pattern + '$', arg):
break
except re.error:
# DENY: Badly-formed filter
return False
else:
# ALLOW: All arguments matched
return True
# DENY: Some arguments did not match
return False
class PathFilter(CommandFilter):
"""Command filter checking that path arguments are within given dirs
One can specify the following constraints for command arguments:
1) pass - pass an argument as is to the resulting command
2) some_str - check if an argument is equal to the given string
3) abs path - check if a path argument is within the given base dir
A typical rootwrapper filter entry looks like this:
# cmdname: filter name, raw command, user, arg_i_constraint [, ...]
chown: PathFilter, /bin/chown, root, nova, /var/lib/images
"""
def match(self, userargs):
command, arguments = userargs[0], userargs[1:]
equal_args_num = len(self.args) == len(arguments)
exec_is_valid = super(PathFilter, self).match(userargs)
args_equal_or_pass = all(
arg == 'pass' or arg == value
for arg, value in zip(self.args, arguments)
if not os.path.isabs(arg) # arguments not specifying abs paths
)
paths_are_within_base_dirs = all(
os.path.commonprefix([arg, os.path.realpath(value)]) == arg
for arg, value in zip(self.args, arguments)
if os.path.isabs(arg) # arguments specifying abs paths
)
return (equal_args_num and
exec_is_valid and
args_equal_or_pass and
paths_are_within_base_dirs)
def get_command(self, userargs, exec_dirs=[]):
command, arguments = userargs[0], userargs[1:]
# convert path values to canonical ones; copy other args as is
args = [os.path.realpath(value) if os.path.isabs(arg) else value
for arg, value in zip(self.args, arguments)]
return super(PathFilter, self).get_command([command] + args,
exec_dirs)
class DnsmasqFilter(CommandFilter):
"""Specific filter for the dnsmasq call (which includes env)."""
CONFIG_FILE_ARG = 'CONFIG_FILE'
def match(self, userargs):
if (userargs[0] == 'env' and
userargs[1].startswith(self.CONFIG_FILE_ARG) and
userargs[2].startswith('NETWORK_ID=') and
userargs[3] == 'dnsmasq'):
return True
return False
def get_command(self, userargs, exec_dirs=[]):
to_exec = self.get_exec(exec_dirs=exec_dirs) or self.exec_path
dnsmasq_pos = userargs.index('dnsmasq')
return [to_exec] + userargs[dnsmasq_pos + 1:]
def get_environment(self, userargs):
env = os.environ.copy()
env[self.CONFIG_FILE_ARG] = userargs[1].split('=')[-1]
env['NETWORK_ID'] = userargs[2].split('=')[-1]
return env
class DeprecatedDnsmasqFilter(DnsmasqFilter):
"""Variant of dnsmasq filter to support old-style FLAGFILE."""
CONFIG_FILE_ARG = 'FLAGFILE'
class KillFilter(CommandFilter):
"""Specific filter for the kill calls.
1st argument is the user to run /bin/kill under
2nd argument is the location of the affected executable
Subsequent arguments list the accepted signals (if any)
This filter relies on /proc to accurately determine affected
executable, so it will only work on procfs-capable systems (not OSX).
"""
def __init__(self, *args):
super(KillFilter, self).__init__("/bin/kill", *args)
def match(self, userargs):
if userargs[0] != "kill":
return False
args = list(userargs)
if len(args) == 3:
# A specific signal is requested
signal = args.pop(1)
if signal not in self.args[1:]:
# Requested signal not in accepted list
return False
else:
if len(args) != 2:
# Incorrect number of arguments
return False
if len(self.args) > 1:
# No signal requested, but filter requires specific signal
return False
try:
command = os.readlink("/proc/%d/exe" % int(args[1]))
# NOTE(dprince): /proc/PID/exe may have ' (deleted)' on
# the end if an executable is updated or deleted
if command.endswith(" (deleted)"):
command = command[:command.rindex(" ")]
if command != self.args[0]:
# Affected executable does not match
return False
except (ValueError, OSError):
# Incorrect PID
return False
return True
class ReadFileFilter(CommandFilter):
"""Specific filter for the utils.read_file_as_root call."""
def __init__(self, file_path, *args):
self.file_path = file_path
super(ReadFileFilter, self).__init__("/bin/cat", "root", *args)
def match(self, userargs):
if userargs[0] != 'cat':
return False
if userargs[1] != self.file_path:
return False
if len(userargs) != 2:
return False
return True
|